Carbureting apparatus



May 23, 1944. G. L.. PRATT CARBURETING APPARATUS 2 Sheets-Sheet l Filed 001'.. 13,' 1941 i WWWMU- ln/ventola @E0/PGE' L. PFHW;

May 23, 1944. Q PRATT 2,349,676

CARBURETING APPARATUS Filed Oct. 13, 1941 2 Sheets-Sheet 2 gwn/7%@ vtional charge of gasoline and air.

atented May 23, 1944 irs f 'rss lenteur FFQE CARBURETBIG APPARATUS George ll... Pratt, Atlanta, Ga., assignor to Motor Power, lino., Atlanta, Ga., a corporation of Georgia 1 (Claim.

This invention is directed to an improved carbureting apparatus for internal combustion engines. The same aims to provide the proper proportioning of the ingredients making up the engine operating charge.

The invention is primarily designed for use in conjunction with the system of treating and reutilizing portions of the engine exhaust gases as a combustible ingredient of an engine operating charge according to my prior Patent No. 2,147.- 670, granted February 21, 1939. In such system the combustion gases exhausting from an engine are centrifuged to effect the removal of portions of the heavier combus'tibly inert ingredients (carbon dioxide and nitrogen) and to provide a reusable combustible portion Whichis enriched in the lighter combustible ingredients (hydrogen, carbon monoxide and methane).

Because the exhaust gases returned to the engine are combustible and constitute an explosive, power-producing ingredient of the engine charge, a substantially less quantity of fresh fuel is required in the charge. Consequently a smaller size metering orifice is required in the carburetor. The usual metering orifice for the high speed nozzle of a carburetor of conventional automobile engines has arelatively small effective opening when the engine operates with a convenating with my system of reutilizing exhaust gases as an operating component of the charge, the

Y size of the metering orifice must be materially reduced, preferably as much as half, more or less. It has been found that the. orifice in the c ase of aV six-cylinder automobile engine of popular make must be so minute in proportions that for-l eign matter tends to clog the orice so as to require frequent cleaning. The same problem is encountered regardless of whether the metering orifice is of the fixed size type.- or is variable in its effective size through the use of a needle valve. Various'xnakes of filters for the gasoline were tried out to overcome the problemof clog- The present invention successfully overcomes the problem and insures relableoperation -of the orifice in supplying the proper proportion of gasoline, or equivalent liquid fuel, independent of the use of a fuel filter.

According to my pri'or Patent No. 2,147,670, above referred to, the centrifuged exhaust gases are drawn back under control of a special regulatory valve located in the Areturn conduit into the intake manifold of ytheengine under the engine suction and therein admixed with air and.

When oper-A ging ofthe orifice without measurable success.

fuel supplied from a carburetor. With the system as so arranged it is found dimcult to maintain a proper proportion of the exhaust gas com- Serial No. 414,870, led October 13, 1941, through the return of the exhaust gases into the carburetor on the air intake side of the throttle valve so that the admission of all components of the charge are subjectv to the regulatory action of the carburetor throttle valve. The carbureting unit of the present application incorporates constructional features for this purpose, and serves in conjunction with the feature above mentioned to cause the carburetor to supply a properly constituted high explosive charge of gasoline, refined exhaust gases and air.

The invention will be understood by reference to the accompanying illustrative drawings and the following detailed description,

In such drawings:

In Fig. 1 is shown a complete charge-forming system wherein the present carbureting apparatus is primarily designed to be used;

Fig. 2 is a View in elevation and partly in section illustrating a carbureting unit embodying the invention; v

Fig. ,3 is an enlarged view in longitudinal section of certain parts shown in Fig. 2;

` Fig. 4 is a schematic view to explain the operation of the carbureting unit of Fig. 2 in conjunction with the system of Fig. 1; and

Figs. 5a, 5b and 5c are comparative diagrammatic views serving to explain certain features of the invention.

A conventional internal bile, engine is shown at l0, the same having an intake manifold Il and an exhaust manifold I2. As in the case of my prior Patent 2,147,670, the exhaust manifold discharges into a centrifugal gas treating device I4 through an exhaust pipe I3, and in such device the exhaust gases under the force of their discharge from the engine are caused to rapidly traverse a helical path which effects a partial s ratification of the gases. The

combustion automotreated'portion o the gases for reuse, enriched in the lighter combustible components of the exhaust, concentrate in the central area of the centrifuge. The residual waste exhaust gases are discharged through an outlet l5. The centrifuged exhaust gases are returned to the engine through pipe i6 which connects with an apertured pipe l1 located centrally of the centrifuge' ld.

The returned exhaust gases are introduced at the air intake side of they carburetor i9 and where, as shown, an air cleaner. i8 is employed, the exhaust return pipe i6 may be led into the carburetor through the housing of the air cleaner.

The carburetor i8 here illustrated is of the down draft type, includes a main body portion fill, and a connecting upper portion Si which for convenience is hereafter referred to as the air inlet portion. The carburetor is provided with a conventional fuel reservoir il in which fuel entering through fuel pipe Q2 is maintained at a substantially constant level by means of a valve (not shown) controlled by oat 43. Connecting passages d@ and d conduct the fuel from the reservoir to the idling passage 66,-and to the main high speed nozzle M. A series of venturis fit, i9 and 5u, or some other conventional arrangement, may-be employed to cause the downward flow of air through the carburetor to draw fuel into the main mixing conduit 50. The car-l buretor at its lower end connects with the intake manifold of the engine. An effective suction, controlled in amount by throttle valve .5Iv in conduit fail is transmitted to the carburetor from the engine and causes the same to function to supply a mixed charge varying in volume according to the setting of the throttle valve.

The upper, or air inlet, portion el of the carburetor has an air inlet or choke valve 52. Ex-

haust gases are introduced into the carburetor under the inrushing flow of air. To this end the carburetor is provided with an extension conduit 53 surrounded, where desired, by an air cleaner i9 wherein air enters at 5H and after passing downwardly between walls 55 and 56 passes upwardly through a. filtering medium 51 into the top portion 5d and thence enters the upper endof extension conduit 53 of the carburetor. The exhaust gas return pipe I6 is provided with a nozzle 59 mounted centrally of conduit 53, and surrounded by a venturi 60 serving to produce an eective suction which will draw exhaust gases from the centrifuging device M (Fig. l) through pipes il and I6 into the carbu retor for admixture with the air in the preliminary mixing chamber 6i on the inlet side of air control valve 52. The suction effect at nozzle 59 is of course determined by the effective suction created in the carburetor by the engine according to the position of throttle valve 5| and the speed of the engine, and moreparticularly by the infiow of air into the carburetor under such suction.

With the construction as shown. it will be evident that the exhaust gases are mixed with the l air ingredient of the charge to be formed prepassage.

combustible operating charge for the engine through intake manifold ll.

To meter the liquid fuel a metering orifice plug 62 is provided between the fuel reservoir 4I and the high speed nozzle 41. For reasons which will hereafter appear it is desirable that such plug shall be submerged and separated from the outlet end of nozzle 41 by a substantial length of Preferably the plug is located in the fuel reservoir 4l, as shown in Figure 2, and provided with a threaded portion 63 seating in a threaded portion of passage 44.

The effective size of the metering orifice is an important factor in the production of a properly proportioned combustible engine charge since it determines the fuel-air ratio of the charge. Since, as mentioned in my prior patent, my system of reutilizing centrifuged portions of the exhaust gases as a supplementary fuel component of the charge requires a smaller quantity of liquid fuel than ina conventional charge forming system wherein the charge is formed only of liquid fuel and air, the effective metering openingv must be substantially smaller. In fact the same must be so small as to frequently become clogged by foreign matter carried in the fuel supply. The problem is the same regardless of Whether a xed metering opening is employed, determined only by the'diameter of the orifice in the metering plug or whether the metering opening is provided by associating a needle valve with the orifice plug which is adjustable re1a.

tive to a valve seat in the orice plug to provide an annular metering opening of varying size. I have discovered, however, that this problem may be successfully overcome in connection with either of the arrangements just mentioned by using a metering orifice of larger effective opening than will pass the quantity of liquid fuel required for the engine charge under any predetermined fuel-air ratio. This is made possible by diluting the liquid fuel with another fluid immediately at or adjacent the point of passage of the liquid fuel through the metering opening, the quantity of the supplementary uid being suilicient that the combined quantity of gasoline and fluid will be accommodated in an opening of suicient size to avoid clogging by foreign matter at the metering point. The diluting fluid will preferably comprise a supplementary air supply which will be subject to the same effective suction as acting on the liquid fuel so that desired proportions of the liquid fuel and air passing through the metering device may be maintained.

The several points just discussed may be understood by reference to the comparative showings in Figs. 5a, 5b, and 5c. In Fig. 5a is shown a metering plug Im having a metering orifice with a diameter a. If liquid fuel alone be supplied through the orice the stream thereof will be of the same size as the diameter of the orifice. If only liquid fuel is to be supplied through the metering orice but a substantial quantity of treated exhaust gases are employed as a component of the fuel charge, the size of the metering orice must be reduced. If, for example, under such conditions only half the quantity of liquid gasoline is required than before, the size of the metering orifice must be diminished by approximately one-half. In Fig. 5b is shown a metering plug 2m having a diameter b which will permit the flow through the orifice of a stream of gasoline only half the size of the stream passed by metering plug lm of Fig. a. It will be understood, of course, that the representative showings in these figures are greatly exaggerated, and that the actual size of the opening in the metering plug 2m will be of approximately pinhole size. An opening of such extremely small size will obviously clog extremely easily. According to-the invention, a metering plugsuch as 3m in Fig. 5 may be employed having an orice of diameter c, substantially larger than the opening of plug 2m, and even larger than the open-v ing of plug im, yetl the same may be caused to pass only the same quantity of liquid fuel as plug 2m of diameter b. Air is supplied to the opening in plug 3m in quantity represented by the partial diameter :z: so as to limit the liquid fuel to the quantity which would pass through the plug if the opening had a size represented by the partial diameter b. As represented in Fig. 5c, and as of the quantity of air supplied through the orice.

t The principles just explained may be applied in a carburetor wherein the metering Vorifice is constituted solely by the bore through a metering plug, by feeding air through a suitable passage to the metering plug bore at the inlet end or at an intermediate point in the length thereof. Likewise the same may be applied in a carburetor where the metering opening is of annular form and provided by coaction of a needle valve with a valve seat in the bore of a metering glllug The latter construction is illustrated in g. Referring again now to Fig. 2 and considering Fig. 3 in conjunction therewith, the metering plug 62 is provided at its inlet. end of its bore 64 with a conical valve seat 65. As before noted themetering plug 52 is located below the liquid -level in the fuel reservoir 4| and is constantly submerged at all times. A needle valve 66 is provided having a tapered end portion lljcoactivcv with valve seat 65 of the plug to provide an adjustable annularv metering orifice. Bore 64 will be of relatively large diameter to insure against cloggingl by foreign matter1 preferably being larger than conventionally employed where` the charge is constituted Lof gasoline and air withl the use of exhaust gases as a supplementary fuel'component. A small bore G8 is provided in the tapered end portion 61 of the needle valve.

The main stem of theneedle' valve is formed by a hollow tube having an interior passage 69 communicating with the bore 68 in the tapered end portion. A threaded hollow sleevelil is secured to the'upper end of the valve stem having a cross bore Il in the upper end thereof beneath enlarged head 12, such crossA bore being in communication with the axial bore of the needle valve. Head 12 of the needle valve is provided with a threaded bore I3 receiving the threaded stem 14 of a further needle valvehaving a tapered lower end 'I5 coactive with a conical valve seat 16 in the hollow sleeve. Valve stem 14. is provided withan enlarged head1? by which the needle valve 14 may be adjusted independently of needle valve 66 to vary the effective annular opening between end l5 and seat 16 and thereby control the quantity of fluid passing through needle valve 66 from cross bore 1l.`

The needle valve assembly just referred to may be supported by a threaded bushing 18 in the top wall 19 of the liquid reservoir 1l with the cross bore 12 communicating with the air exteriorly of the carburetor. The size of the main metering orice at plug 62 may be varied by turning head 12 to raise or lower the needle valve stem 66, thereby to vary the quantity of liquid fuel passing from the reservoir 4l through bore 64 of the metering plug 62. The quantity of air admixed with the liquid fuel at the metering point in the inlet end of plug 64 may be varied in relation tc the quantity of gasoline independently of the size of the main metering orifice at plug St by turning head`11 of the upper needle valve 14 which controls the flow-of air through the hollow stem of the needle valve.

In view of the fact that the flow of both air and gasoline through the metering orifice of plug 64 is determined by the effective engine suction acting in the carburetorl under control of the throttle valve, and more specifically, by the iiow of fluid under such suction through the venturis 48 and 49 past the outlet end of the high speed nozzle 41, the supply of supplementary air and the liquid fuel'will be maintained in proper proportion to limit the liquid fuel to the quantity required even though the effective opening provided by the coaction of the needle valve end 51 with the valve seat B5 of plug 641s of substantially larger size than would limit the liquid fuel to the quantity required if the supplementary air supply were not employed to dilute the liquid fuel.

The position of the metering plug $4 in the liquid reservoir is desirable so that the supplementary air and fuel are required to traverse a substantial distance, as represented by the combined lengtlt of passages 44 and 45 before being discharged 'from the outlet end of nozzle 41. Through this arrangement the supplementary air is given an opportunity to become at least partially saturated with the liquid fuel so as to effect partial vaporization of the fuel before discharge from the nozzle. course. initially promoted by reason of thefact that the air is introduced into the gasoline in the form of alfine stream at the metering point, so that both the air and liquid fuel are reduced to a more or less comminuted condition incident to their admixture.

The complete operation of the carburetor as shown in Fig. v2 in producing anengine charge, and more particularly the operation thereof in conjunction with the use of treated exhaust gases as a component of the charge, will be understood by reference to Fig. 4. As therein shown, the intake manifold of the engine creates an eective suction in the carburetor which serves to draw,

the main air supply into the carburetor con,- duit, and,at the same time to draw centrifug/e'd poiticns of the exhaust gases from the centrifugal device into the carburetor through the exhaust gas nozzle mounted in the air supply inlet about which the inflowing air rushes through a surrounding venturi. The main throttle valve of the carburetor determines the ef- 'fective engine suction acting therein and the quantity of both exhaust gases and air under.

varying conditions of engine speed and load. The liquid fuel supply supplemented and diluted by an auxiliary air supply are combined Such admixture is, of

and metered by passing through a metering orice as heretofore explained, and after preliminary admixture discharged into the main car.- bureting mixing chamber for admixture with the previously admixed exhaust gases and main air supply in the main carburetor mixing chamber, the quantity of liquid fuel and air being both controlled by the eiective suction in the mixing chamber, and particularly by reason of the rush of mixed air and exhaust gases through the venturi, or venturis, surrounding the high speed fuel nozzle. The engine charge is completely admixed in the carburetor and is passed therefrom into the engine intake manifold and thence to the engine cylinders.

It will be understood that metering plug t2 with its manuallyiadjustable needle valve control 66 need not be the sole metering means for delivering fuel from the reservoir to the high speed nozzle. In many cases an additional cooperating metering device will be employed comprising a metering plug having an opening controlled by a metering pin. which is automatically regulated through the carburetor throttle valve.

The special construction of the needle valve performs an additional beneficial function bw sides supplying the auxiliary air for limiting the amount of liquid fuel passed through the metering plug 5t. When the engine is at idling speed and the high speed fuel nozzle lll is inoperative, only a small quantity of fuel is supplied from the fuel reservoir lli to the idling speed fuei supply passage 66, and no auxiliary air is drawn in through the needle valve. Under such conditions fuel from the reservoir backs up through bore 58 into the enlarged interior 68 of the,

needle valve seeking the same level prevailing in the reservoir et. When the high speed nozzle di comes into operation to increase the speed of the engine by opening wider the butterfly valve '5L the increased suction acts to increase the ow through the metering plug 62. Under these conditions the fuel which has accumulated in portion 69 of the needle valve will be drawn out through bore 68 to supplement the fuel admitted to the metering plug from the reservoir, and no auxiliary air will be supplied through the needle valve until the accumulated fuel therein has been exhausted. This increased quantity of fuel which momentarily enriches the carburetor charge at the moment of acceleration is very desirable to prevent momentary skipping or sluggishness of the engine. In the past carburetors have been built to embody an accelerating pump for momentarily injecting an additional quantity of fuel during acceleration. With the present arrangement, through the construction of the needle valve with an enlarged portion 69 as shown in Fig. 3, it is found possible to dispense Withsuch an accelerating pump and thereby simplify .the carburetor construction.

The carburetor, as shown in Fig. 2, is provided with an exhaust gas delivery nozzle 59 located therein on the air intake side of throttle valve 5l. Preferably, th'e same is located on the air intake side of the high speed nozzle 4l and choke valve 52. As shown, nozzle 59 is mounted" in extension conduit 53 of `the air intake conduit. In the present form the nozzle is mounted in a central opening and covering 8d of air cleaner I 9 and secured to such cover through nuts 82 and 83'. Of course the air cleaner may be dispenser'. with, or again may not be manufactured and sold as a part of the carbureting unit, and therefore it may be desirable to mount nozzle 59,

permanently or detachably, centrally of the air intake conduit proper of the carburetor through the use of any suitable type of mounting which will not interfere with the free flow of air into the carburetor around nozzle 5S. Regardless of the exact position of nozzle 59, it is important that venturi 60 be provided to surround the nozzle so that the inflow of air through the venturi will produce an adequate suction at the nozzle to draw exhaust gases into the carburetor in suficient quantity to constitute a balanced charge with the air and fresh fuel. It may be explained in this connection that the effective suction in the carburetor'from the engine is relatively low and incapable of withdrawing exhaust gases into the carburetor in sulcient quantity to constitute a primary component of the engine charge. This is particularly true under conditions where the engine is running at relatively low speed and the throttle valv'e is only slightly open. The use of the venturi, due to the increased velocity therethrough of the incoming air serves to produce an increased local suction effect at nozzle 5@ and result in the delivery of an adequate exhaust gas supply which is automatically varied according to the volume of air admitted under adjustment of the main throttle valve.

fn the improved system shown in Fig. 2 the centrifuged exhaust gases are returned tothe carburetor from the centrifuge It under the suction developed at nozzle 59 in the carburetor, hence the inflow of air into the carburetor determines the quantity of the exhaust gases returned rather than the return flow of exhaust gases determining the quantity of air admitted to the carburetor. As pointed out inemy prior Patent No. 2,147,670, the exhaust gases in the state in which they are discharged from the engine are not in suitable condition for use as a fuel component of the engine charge, and cannot be returned in any substantial quantity without inteidering with combustion of the fresh hydrocarbon fuel component and consequential loss of power in the engine. However, the centrifugal treatment of the exhaust gases conditions them for use as a primary fuel component of the engine charge so as to enable them to be returned in substantial quantity with resulting economy in the fresh fuel consumption. It will therefore be evident that the present carburetor, for employment in such a system of centrifug'ing and re,- using the exhaust gases, must be so constituted that the fuel metering mechanism is so designed as to restrict'the delivery of fresh fuel to an amount such as to compensate foi` the supplementation thereof by combustible fuel values of the returned exhaust gases, and similarly the means above described for delivering the exhaust gases into the carburetor should be so designed as to deliver the exhaust gases in suc ent quantity to enable an appreciable savings to be effected in the consumption of the fresh fuel and to maintain a balance in the proportion of the centrifuged exhaust gases to the proportions of fresh fuel and air.

I am aware that various proposals have been made for introducing exhaust gases, in the state in which they are discharged from the engine and usually under theV pressure of their discharge, into the carburetor. In such prior devices the exhaust gases were utilized for available heat to promote vaporization of the liquid fuel, and/or through their delivery under pressure into the carburetor to aid in the delivery of air or liquid fuel. By reason of the condition in which the exhaust gases were returned they could not be used in any appreciable amount, nor could they function as a combustible fuel component of the charge. Consequently, and contrary to the present invention, the careful proportioning of the exhaust gases to the fresh fuel and air in such prior devices was not necessary, and similarly, the provision of means for restricting the fresh fuel to any appreciable extent was not a problem since the exhaust gases in the form and quantity returned could not function as a fuel component and effect a saving in the fresh fuel consumption.

The complete charge forming system for an engine wherein centrifuged exhaust gases are combined as a primary component of the engine charge hasbeen explained in the present application to make clear the utility of certain fea'- tures o'f the carburetor construction. The present application is directed to the carbureting unit per se, and the improved charge forming system as such forms the subject-matter of my separate copending application, Serial No. 414,870, led October 13, i941.

It will be -evident that the carbureting unit herein shown is merely illustrative, and that the features of carburetor construction constituting the invention may be incorporated in carburetor-s of other types in a, variety of Ways without departing from the intended scope of the invention.

I claim:

In anA internal combustion engine carburetor,

a mixing chamber, a main air intake delivering air to the mixing chamber, a liquid fuel delivery nozzle extending into the mixing chamber, a

liquid fuel reservoir, a fuel delivery passage connecting the lower portion of the fuel reservoir and said fuel delivery nozzle, fuel economizing means diminishing the liquid fuel required to be delivered through said fuel delivery passage to the mixing chamber to form a combustible charge, said fuel economizing means comprising a second nozzle adapted to deliver charge forming components of the engine exhaust gases to the mixing chamber for admixture with the fuel and air, submerged fuel metering means in the fuel delivery passage having an opening of larger area than required to deliver the quantity of fuel necessary for the combustible chargathe size of said opening decreasing the likelihood of clogging of the opening by foreign matter such as may be delivered with the fuel, and means for restricting the quantity of liquid fuel delivered through said metering opening to the quantity o'f fuel required by the charge formed with the air and exhaust gas components, andy comprising a needle valve having an air delivery passage therein delivering air for passage through the metering opening with the fuel and being adjustable to vary the ratio of` fuel to air passing through the meteringV opening.

GEORGE L. PRATT. 

